Jupiter in infrared light – spectra of the brightest regions show some signs of the presence of water, but cannot map the deep, drenched interior. Credit: ESO\/L.N. Fletcher<\/p><\/div>\n
Certain wavelengths of light can start to probe down through these topmost cloud layers, like removing the skin of an onion to see what lies beneath.\u00a0 For example, Earth-based telescopes can use observations of Jupiter’s infrared glow at 5 microns to peer through gaps in the ammonia ice clouds, such as those recently released by the Very Large Telescope in Chile.\u00a0 Previous spacecraft, such as Galileo and Cassini, have had instruments that can observe Jupiter in this spectral `window’, and allowed us to place lower limits on the amount of water present (around 0.04% by volume).\u00a0 However, they never sense down deep enough to see the amount of water in the deeper atmosphere, which is expected to be in the 0.1-1.0% range, depending on the different models used.\u00a0 Juno carries a similar infrared instrument called JIRAM, provided by the Italian Space Agency, which will perform similar measurements.\u00a0 But the deep water abundance remains out of reach for these infrared\u00a0mappers.<\/p>\n
A much better solution, then, is to actually send a probe into Jupiter itself.\u00a0 And that’s precisely what we did in 1995 with the Galileo probe, which carried all the sensors required to sniff out the gases and clouds in Jupiter’s cloudy layers.\u00a0 However, with only one probe there’s always the risk that you’ll find a region that isn’t representative of the full planet.\u00a0 Imagine trying to understand the amount of water on Earth if you only sampled the Sahara desert.\u00a0 The probe descended into a location known as a ‘hotspot’ just north of the equator, where powerful downwelling regions dried the atmosphere out and removed almost all traces of water.\u00a0 The probe transmission ended at 20 bar of pressure, below the expected altitude of the water cloud (around 5-7 bar), but still without finding the deep abundance.\u00a0 The maximum was 490 ppm near 20 bar (0.05% by volume), around 30% of the solar abundance.\u00a0 Based on Galileo’s measurements of other species, like methane and ammonia, we’d expect that value to be more like 400-1000% of the solar abundance.<\/p>\n
![\"Mapping](\"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/files\/2016\/07\/microwave-1024x877.jpg\")
Mapping of Jupiter’s deep water and ammonia, key condensible species, far below the obscuring clouds. Credit: NASA<\/p><\/div>\n
<\/p>\n
It’s this mystery that’s driving Juno, and its microwave radiometer experiment.\u00a0 Microwave light is another way of peering below the topmost clouds, and this should give us access down to 100 bar of pressure to see the distribution of water down at great depths.\u00a0 We’ll be going deeper into the churning, convective weather layer than ever before to understand not only the bulk abundance of water, but also its distribution.\u00a0 Maybe there’s more water available beneath the belts to power the moist convection and lightning storms that we see there?\u00a0 But it’s a balancing act, and too much water actually stabilises the atmosphere and prevents convection – maybe that’s what’s happening beneath the white zones, where we don’t see as much convection?\u00a0 Or is water really depleted throughout the cloud forming region, as the Galileo probe results suggested?\u00a0 Juno is about to provide the answer.<\/p>\n
<\/p>\n
<\/p>\n
At the same time, we’ll be amassing data from Earth that reveals the temperature, cloud and compositional structure above the clouds to see how this relates back to the distribution of water far below.\u00a0 Will the deep atmospheric dynamics be different to what we’re used to above Jupiter’s clouds?\u00a0 We hope to finally have a handle on the ‘Jovian water cycle’ that powers the weather on this gas giant world.<\/p>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Water, water, everywhere. \u00a0 Dr. Leigh Fletcher appeared on this month’s episode of BBC Sky at Night to discuss Juno’s goals at Jupiter, and describes the importance of Jupiter’s water in this new post. If our ideas about the formation of giant planets stand up to the observational tests of the Juno […]<\/p>\n","protected":false},"author":256,"featured_media":103,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[20,11,16],"class_list":["post-102","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science","tag-composition","tag-jupiter","tag-weather"],"_links":{"self":[{"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/posts\/102","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/users\/256"}],"replies":[{"embeddable":true,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/comments?post=102"}],"version-history":[{"count":5,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/posts\/102\/revisions"}],"predecessor-version":[{"id":108,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/posts\/102\/revisions\/108"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/media\/103"}],"wp:attachment":[{"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/media?parent=102"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/categories?post=102"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/wp-json\/wp\/v2\/tags?post=102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"Jupiter](\"https:\/\/staffblogs.le.ac.uk\/leicester-to-jupiter\/files\/2016\/06\/eso1623a-296x300.jpg\")